Short duration timer



May 23, 1961 H. HILKEMEIER SHORT DURATION TIMER Filed March 2, 1959 INVENTOR. Herbert Hi/keme/er BY 6; J8? 5M States Patent SHORT DURATION TIMER Herbert Hilkemeier, Lancaster, Pa., assignor to Hamilton Watch Company, Lancaster, Pa., a corporation of Pennsylvania Filed Mar. 2, 1959, Ser. No. 796,611 13 Claims. (Cl. 307-141.4)

This invention relates to a short duration timer and in particular to a timing mechanism which is capable of producing delay intervals of extremely short time with great accuracy and dependability.

In many instances it is found desirable to use a given pulse or other electrical signal to trigger or instigate a reaction in another circuit but only after a certain definite and predetermined time delay. For example, in military applications this time delay may be to permit a given missile or projectile to clear the launching pad, muzzle or other firing media. Alternatively it may be the signal which causes the missile to arm itself. The time delay that is sought in many of these applications is extremely short, not in excess of one second and, in some applications a given time delay mechanism may be used for successive cycles. It is therefore desirable to be able to recock the delay mechanism in an automatic manner.

According to the present invention, it has been found that it is possible to provide an improved timer of the foregoing type wherein a balance wheel and hairspring are utilized and by proper adjustment of the strength of the hairspring and the weight of the balance wheel a time delay range can be established from approximately onefourth of a second to one half of a second with an error of less than five milliseconds.

It is accordingly a primary object of the present invention to provide an improved short time delay device having a high degree of accuracy.

It is another object of the invention to provide an improved short duration timer utilizing a balance wheel and hairspring to provide accurate short duration timing intervals.

It is another object of the invention to provide an improved short duration timer of the foregoing type which is capable of automatically recocking itself for recycling.

It is still a further object of the invention to provide a short duration timer of the foregoing type which is simple of construction, economical to manufacture and relatively foolproof in operation.

These and further objects and advantages of the present invention shall become more apparent upon reference to the following specification and claims and appended drawing in which:

Figure 1 is a schematic representation of the delay mechanism of the present invention; and

Figure 2 is a partial vertical section taken on the line 2-2 in Figure 1.

Referring to the figures of the drawing, a balance wheel is vertically mounted on a stafi 11 in a suitable frame member indicated generally at 12. The lower end of the staff 11. is journalled in frame 12 while the upper end is journalled in a conventional bridge, not shown. A hairspring 14 has one end attached to the balance wheel 10 and frame 12 in a manner customary in the watchmaking art. The hairspring 14 is capable of maintaining oscillatory motion in the balance wheel 10 in a counter-clockwise direction designated as the forward di- Patented May 23, 1961 rection in this specification, and in a clockwise direction, designated as the reverse direction in this specification. A number of bored holes 15 extend through the balance wheel 10 and are arranged in symmetrical fashion. By varying the size of holes 15 the weight of the balance wheel 10 may be altered which together with the strength of hairspring 14 is determinative of the time delay produced.

The balance wheel 10 is provided with a pin 16 which extends radially outwardly from the periphery thereof and is engaged in a groove or detent 18 of a latching bar designated generally at 20. Latching bar 20 is pivotally attached to the frame member 12 at 22 and provided with an extension 24 remote from the groove 18. A solenoid 26 has a plunger 28 slidably received therein and this plunger carries at its end a contact member 30 which is capable of pulling the latching bar 20 from its latched position, as shown in the drawing, to an unlatched position by retraction of the plunger 28 into the solenoid in the direction of the arrow. The balance wheel is in a cocked position when in the latched position shown in the drawing.

A cam 32 is mounted on staff 11 for rotation with the balance wheel 10 and hairspring 14 and is used in recocking the timing mechanism.

A pin 34- extends downwardly from the balance wheel 10 as is best seen in Figure 2. A bar 36 is pivotally mounted at 38 .to the frame member 12 and is provided with an actuator 40 at one end and a pawl-like member 42 atop the other end. The pawl-like member 42 is pivoted to the bar 36 at 43 and is spring urged in a clockwise direction to the limiting position shown. The pawl is capable of rotation against the action of its spring in a counter clockwise direction, but is restrained from rotating in a clockwise direction by the edge 43 on block 45 mounted therebeneath. As a result of this mounting the pawl-like member 42 is adapted to yield to the pin 34 as the balance wheel 10 rotates in a forward or counterclockwise direction. However, upon rotation in a reverse or clockwise direction, the pin 34 strikes the edge 35 of the pawl-like member 42 and pivots bar 36 about pivot point in a counter-clockwise direction to momentarily close movable switch contacts 44 and 46 of a double pole switch indicated generally at 48.

The electrical system will now be described. A pair of input signal terminals are indicated at 1 and 2 and a pair of load terminals are shown at 3 and 4 with a load indicated generally at 50. Power supply terminals are provided at 5 and 6. In a specific embodiment the timer may utilize a 28 volt DC. power supply and the pulse voltage applied to the signal terminals 1 and 2 also may be 28 volts D.C. although other voltages may obviously be used.

A rotary solenoid generally indicated at 52 is mounted on the frame 12 and is provided with an actuating coil 54. Rotary solenoid 52 is further provided with a pair of radial arms 56 and 58 which are adapted to actuate switches indicated at 62, 64 and 66. Arm 56, also carries a cam follower 60 adapted to engage the periphery of recocking cam 32 as the rotary solenoid rotates counterclockwise.

Switch 62 is provided with an actuator arm 68 bent to engage a stop button 69 on the rotary solenoid 52 so that plunger 70 maintains the contact arm 72 of the switch 62 in a closed position. Thus, switch 62 is normally closed when the rotary solenoid is deenergized and at rest. A stop button 76 carried by the rotary sole noid 52 contacts the actuator arm 74 of switch 64 which acts through plunger 78 to maintain contact arm 80 in an open position. Thus, switch 64 is normally open.

Switch 66 is normally closed. However, when the rotary solenoid actuating coil 54 is energized, rotary solenoid 52 rotates in a counter-clockwise direction as indicated by the arrow. This causes arm 58 to depress plunger 82 and open contact arm 84 and switch 66. Similarly, as stop button 69 rotates with the rotary solenoid 52 in a counterclockwise direction actuator arm 68 and plunger 70 are released to permit contact arm 72 to open. As stop button 76 rotates with the rotary solenoid 52 in a counterclockwise direction, actuator arm 74 follows it and permits plunger 78 to move and contact arm 80 to close.

A normally open switch 86 is provided in series with switch 62. When solenoid 26 is actuated, plunger 28 moves upward in the direction of the arrow to permit extension 24 of the latching bar 20 to depress plunger 88 thereby causing contact arm 90 to close the contacts of switch 86.

Referring to the lower right hand corner of the drawing there is seen a first relay 92 provided with an actuating coil 94. Relay 92 is provided with movable contact elements 96 and 98 which are normally open when coil 94 is deenergized.

Referring to the upper right corner of the drawing a second relay is indicated at 100. This relay is provided with an actuating coil 102, movable contact element 104 which is normally closed, and movable contact elements 106 and 108 which are normally open.

In operation, a start signal is applied across input signal terminals 1 and 2. This start signal is applied through lead 110, closed movable contact element 104 and lead 112 to a coil 114 of solenoid 26. The return path is through leads 116 and 118 and lead 120. When coil 114 is energized, by the application of this signal, plunger 28 moves upward in the direction of the arrow to unlatch the latching bar 20 from pin 16 on balance wheel and this starts the timing cycle. As latching bar pivots in a clockwise direction, extension 24 contacts plunger 88 to close the contact arm 90 of switch 86. This causes current to flow through a holding coil 122 on the solenoid 26 from the power supply terminal 6, lead 124, coil 122, lead 126, through switch 86, lead 128, through normally closed switch 62, lead 130, and lead 132 back to power supply terminal 5. This causes the latching bar 20 to be held free from the balance wheel 10 even though the start signal is only of a momentary duration.

Balance wheel 10, driven by its hairspring 14, begins its timing cycle of rotation which lasts for approximately 270. The inertia of the balance wheel causes it to continue its rotation for approximately another 270 until the hairspring stops and eventually reverses its rotation. When the balance wheel 10 rotates in a counterclockwise or forward direction, pin 34 passes the pawl-like member 42 mounted on bar 36 without causing pivotal movement of the bar. That is to say, the pawl-like member itself rotates counterclockwise against its return spring but does not move the bar 36. However, when the balance wheel 10 returns in a clockwise or reverse direction, pin 34 engages the edge 35 of pawl-like member 42 to cause the bar 36 to pivot about point 38 and to momentarily close switch 48. As switch 48 closes, output terminals 3 and 4 are short circuited by way of leads 134 and 136 thereby applying a short across load 50. This terminates the time delay cycle. It will be obvious that the termination of the timing cycle may also bring about the opening of a circuit by substitution of appropriate switches.

As soon as switch 48 closes, relay 92 is energized through the circuit from terminal 6 of the power supply, lead 124, switch 48, leads 133, 140, coil 94 and lead 132. As soon as switch 48 closes and relay 92 is energized, movable contact 96 of relay 92 moves away from open contact 144 to engage lead 14-6. This applies a holding circuit across output terminals 3 and 4 by way of leads 146, 148, and 150. Movable contact 98 of relay 92 moves away from its open contact 154 to engage lead 156 thereby energizing coil 54 of rotary solenoid 52 by way of leads 158, switch 66, leads 160 and 156, contact element 98, lead 140, coil 54, leads 162 and 132 and power supply terminal 5. This, in turn, causes arm 56 to rotate with rotary solenoid 52 in a counterclockwise direction to engage the cam 32 on the balance wheel. Normally closed switch 62 is permitted to open as stop button 69 rotates in a counterclockwise direction thereby deenergizing coil 114 of solenoid 26. Normally open switch 64 is closed as stop button 76 on rotary solenoid 52 rotates in a counterclockwise direction permitting actuator arm 74 and plunger 78 to follow and thereby permitting contact arm to close.

If a start signal is still present across terminals 1 and 2, this causes relay to be energized through leads 120, 118, 116, switch 64, lead 164, coil 102., leads 166 and back to input signal terminal 1. This, in turn, causes movable contact element 106 in relay 100 to close to lock relay 100 in an actuated position. The path of current flow which effects this is through lead 120, movable contact element 106, leads 168 and 164, coil 102, leads 166 and 110 back to input signal terminal 1. Movable contact element 108 closes thereby paralleling the load element 50 through lead 170, movable contact element 108, leads 172 and back to terminal 3. Movable contact element 104 opens thereby deenergizing coil 114 and permitting plunger 28 to return to its deenergized position where the latching bar 20 may engage pin 16 on balance wheel 10. In this manner, arm 56 may, by engaging cam 32 drive the balance wheel clockwise from. its broken line position in Figure l to relatch balance wheel 10 by causing engagement of pin 16 in groove 18 of the latching bar 20.

As arm 58 contacts plunger 82, switch 66 is opened thereby deenergizing relay 92. Rotary solenoid 52 is thereby deenergized and returned to its normal position. The mechanism is now recocked and when the pulse is removed from the input signal terminals 1 and 2, relay 100 will be deenergized and the mechanism will be ready for its next cycle. If the starting pulse were removed prior to the time that switch 64 closed, relay 100 would not be energized and the mechanism would be ready for its cycle as soon as rotary solenoid 52 returned to its normal position.

To summarize the sequence of operation, the balance wheel 10 is held cocked against the tension of hairspring 14 by latching detent 18 on bar 20. A start pulse applied to terminals 1 and 2 energizes solenoid 26 to retract detent 18 and free balance wheel 10. The balance wheel rotates in a counterclockwise direction carrying the pin 34 past the pawl-like member 42 without substantially moving bar 36. This rotation ultimately winds the hairspring 14 which reverses the direction of rotation of the balance wheel. The balance wheel now rotates clockwise and the pin 34 strikes the edge 35 of pawl-like member 42. This rotates bar 36 counterclockwise and actuator 40 closes switch 48 which is the action which was timed. That is to say the timed interval extends from the moment the balance wheel is released to the moment its return rotation actuates bar 36.

The balance wheel is recocked by subsequent energization of rotary solenoid 52 which rotates arm 56 counterclockwise to cause cam follower 60 to engage cam 32 and drive the balance wheel clockwise. Detent 18 relatches in the position shown in the drawing and the balance wheel is recocked for another cycle.

A relay 92 is energized as soon as the switch 48 closes momentarily to maintain a short circuit across the load 50 until rotary solenoid 52 completes its counterclockwise rotation and opens switch 66. If the original start signal is of such a duration as to be still present when the rotary solenoid 52 starts to rotate in a counterclockwise direction to recock the balance wheel, a second relay is energized to maintain a short circuit across the load 50 and to deenergize'the coil 114 of solenoid 26 so that the latching bar 20 may be released to a position where it may relatch the balance wheel. As soon as the start signal is removed, the relay 100 is deenergized and the timer stands ready to begin another sequence.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiment is therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

l. A timing device for performing a switching function at the end of a predetermined period of time, comprising, a frame member, rotary means mounted for rotation on said frame member, means for latching and unlatching said rotary means, means for driving said rotary means in both a forward and a reverse direction, ratchet means pivotally mounted to said frame member, means for applying a start signal to unlatch said latching means, switch means for performing said switching function, first cam means mounted on said rotary means to actuate said switch means through said ratchet means to perform said function when said rotary means is traveling in the reverse direction, second cam means mounted for rotation with said rotary means, and cam follower means for drivingly engaging said second cam means to restore said rotary means to a latched position.

2. A timing device as described in claim 1, including a rotary solenoid carrying said cam follower means and actuated by said switch means to drive said cam follower means into engagement with said second cam means.

3. A timing device as described in claim 2 including relay means actuated by said switch means to energize said rotary solenoid.

4. A timing device as described in claim 3 including means carried by said rotary solenoid to deenergize said relay means after said rotary means is relatched.

5. A timing device for performing a switching function at the end of a predetermined period of time, comprising, a frame member, rotary means mounted for rotation on said frame member, means for latching and unlatching said rotary means, means for driving said rotary means in both a forward and a reverse direction, ratchet means pivotally mounted to said frame member, means for applying a start signal to said latching means, a holding circuit to maintain said latching means in an unlatched position, and switch means for performing said switching function, said ratchet means cooperating witli said rotary means to actuate said switch means when said rotary means is traveling in the reverse direction.

6. A timing device for performing a switching function at the end of a predetermined period of time, comprising, a frame member, rotary means mounted for rotation on said frame member, means for latching and unlatching said rotary means, means for driving said rotary means in both a forward and a reverse direction, ratchet means pivotally mounted to said frame member, means for applying a start signal to said latching means, a holding circuit to maintain said latching means in an unlatched position, switch means for performing said switching function, first cam means mounted concentrically with said rotary means, second cam means mounted for rotation with said rotary means to actuate said switch means through said ratchet means when said rotary means is traveling in the reverse direction, cam follower means adapted to engage said first cam means to restore said rotary means to a latched position, a rotary solenoid carrying said cam follower means and actuated by said switch means to drive said cam follower means into engagement with said cam means, first relay means actuated by said switch means to energize said rotary solenoid and a normally closed switch actuated by said rotary solenoid to interrupt said holding circuit to permit said rotary means to be relatched.

7. A timing device as described in claim 6 including a normally open switch actuated by said rotary solenoid to actuate a second relay means, said second relay means provided with a first pair of contacts to deenergize said latching means to permit said rotary means to be relatched.

8. A timing device as described in claim 6 wherein said second relay means is provided With a second pair of contacts to energize a holding circuit for said second relay means for the duration of said start signal.

9. A timing device as described in claim 6 wherein said second relay means is provided with a third pair of contacts to provide a holding circuit for said switching function to permit said first relay to be deenergized.

10. A timing device comprising a balance staff, a balance wheel carried for oscillatory movement by said balance staff, a hairspring secured to said balance staff for controlling the movement of said balance wheel, means for holding said balance wheel in a cocked position, a cam carried by said balance staff, and rotary means energized by oscillation of said balance Wheel through a predetermined cycle for cocking said balance wheel, said rotary means bearing on said cam to rotate said balance wheel through an angle of more than 180 into its cocked position.

11. A timing device according to claim 10 wherein said rotary means comprises a rotary solenoid carrying an arm having a cam follower at its outer end for driving said cam and cocking said balance wheel by a single pass of said arm.

12. A timing device comprising a balance staff, a balance Wheel carried for oscillatory movement by said balance staff, a hairspring secured to said balance staff for controlling the movement of said balance wheel, means for releasably holding said balance wheel in a cocked position, and rotary means energized by oscillation of said balance wheel through a predetermined cycle for cocking said balance Wheel through an angle of more than 180 by movement of said rotary cocking means through an angle of less than 13. A timing device according to claim 12 wherein said rotary cocking means drives said balance Wheel through an angle of approximately 270 from its rest position.

References Cited in the file of this patent UNITED STATES PATENTS 1,494,986 Behm May 20, 1924 2,699,829 Burnette Jan. 18, 1955 2,743,775 Mitchell May 1, 1956 2,868,287 Estey Jan. 13, 1959 2,891,617 Wharton June 23, 1959 FOREIGN PATENTS 399,794 Germany Sept. 23, 1924 

